PD-1 blockade in Hodgkin's lymphoma: learning new tricks from an old teacher.

INTRODUCTION: Classical Hodgkin's Lymphoma (cHL) is characterized by genetic reliance on the PD-1 pathway. Rapid accumulation of data describing the role and efficacy of PD-1 and its blockade warrants a focused review. AREAS COVERED: In this article, we will review the unique biologic features that predispose cHL to PD-1 inhibition, current data regarding the safety and efficacy of PD-1 inhibitors in the treatment of cHL, biomarkers of immune response, ongoing clinical trials with PD-1 inhibitors, as well as areas of uncertainty. Expert commentary: The biologic and genetic underpinnings of cHL make it unique among all malignancies in its exquisite sensitivity to PD-1 inhibition. High response rates to single agent PD-1 inhibitors in early phase clinical trials serve as further proof of concept. These data strongly support continued clinical investigation of the evolving role of PD-1 inhibition in classical Hodgkin's lymphoma, including the optimal sequence, setting, and combination to best exploit the immunologic properties of this disease.